The most satisfying successes of all are when you can get them to admit they made a mistake. I'm not sure I'm particularly good at doing that, but the trick seems to be being friendly, calm, and humble. Nothing even slightly confrontational.
Although inside I often want to angrily tick off a driver for some thoughtless and stupid action, I'd really much rather they learnt from their mistake and realised how it badly affected me. The second win is a calm ignore them attitude, followed up by a letter and video clip to the company transport manager.